Rudolph W. Giuliani, President Trump’s lead personal lawyer, said on Sunday that the president never had a conversation last year with James B. Comey, then the F.B.I. director, about ending the investigation into the fired national security adviser Michael T. Flynn, contradicting a memo Mr. Comey wrote at the time.

Mr. Giuliani’s statement, made during an appearance on CNN’s “State of the Union,” also appeared at odds with his own previous comments. While the White House has previously denied that Mr. Trump had asked Mr. Comey to drop the investigation, Mr. Giuliani had suggested that the two had discussed the inquiry, but in a way different from Mr. Comey’s account.

“There was no conversation about Michael Flynn,” Mr. Giuliani said Sunday. “The president didn’t find out that Comey believed there was until about — I think it was February when it supposedly took place. Memo came out in May.”

He continued: “And in between, Comey testified under oath that in no way had he been obstructed at any time. And then, all of a sudden, in May, he says he felt obstructed, he felt pressured by that comment, ‘You should go easy on Flynn.’ So we — we maintain the president didn’t say that.”

When the “State of the Union” host, Jake Tapper, noted that Mr. Giuliani had previously told ABC News that Mr. Trump had suggested that Mr. Comey give Mr. Flynn a break, Mr. Giuliani insisted he had never made that comment.

“That’s crazy. I have never said that,” Mr. Giuliani said. “I have always said the president denies it. Look, it’d be easier for me if the president did say that. Jay and I could defend that,” he said, referring to Jay Sekulow, another of the president’s lawyers.

Last month, when pressed on ABC News by George Stephanopoulos about whether Mr. Trump told Mr. Comey he hoped he could see his way to ending the Flynn case, Mr. Giuliani interrupted him to say that Mr. Trump did not say that.

“What he said to him was, ‘Can you give him a break?’” Mr. Giuliani said in that interview.

In a letter that Mr. Trump’s previous lead lawyer, John Dowd, wrote to the office of the special counsel, Robert S. Mueller III, the president’s legal team pointed out that Mr. Comey had never mentioned his memory of their February 2017 conversation about Mr. Flynn in previous testimony before Congress, and recalled it only after Mr. Trump fired him in May 2017.

In his memo, Mr. Comey wrote that Mr. Trump had told him, “I hope you can see your way clear to letting this go, to letting Flynn go.”

The memo was part of a paper trail Mr. Comey created to document what he perceived as the president’s improper efforts to influence an investigation. He is now seen as a key witness in the portion of the Mueller investigation that deals with obstruction of justice.

Mr. Flynn, who was Mr. Trump’s first national security adviser, pleaded guilty in December to lying to the F.B.I. about his conversations with the Russian ambassador, becoming the first senior White House official to cut a deal to cooperate with the special counsel.

A version of this article appears in print on , on Page A13 of the New York edition with the headline: New Claim By Giuliani On Comey And Trump. Order Reprints | Today’s Paper | Subscribe